The Effects of Creatine and Chronic Low Frequency Stimulation on Muscle Fiber Cross-Sectional Area
Bibliographic record
Abstract
We have shown that creatine (Cr) loading of rat muscle attenuates fast-to-slow fiber type transformations in plantaris after wheel running and in tibiailis anterior (TA) after chronic low frequency stimulation (CLFS). A model of muscle endurance training, CLFS alone also induces decreases in fiber cross-sectional areas (CSA's). PURPOSE: To test the hypothesis that attenuated fast-to-slow fiber type transformations in Cr loaded rat TA after 10-days(d) of CLFS will correspond to larger CSA of type II fibers. METHODS: Sprague-Dawley rats were randomly assigned to one of four groups: Cr + CLFS (Cr-Stim), CLFS (Con-Stim), Cr + sham (Cr-Sham) or sham (Con-Sham). CLFS (10 Hz, 10 h daily, impulse width 380 μs) was applied to the left TA via electrodes implanted across the common peroneal nerve; the right contralateral TA served as an internal control. Animals in the Cr groups consumed a solution of 1% Cr in 5% dextrose for 10-d before CLFS began and during 10-d of CLFS; control groups received 5% dextrose. Standardized regions of serial sections of left and right TA's were immunohistochemically stained for adult myosin heavy chain (MyHC) isoforms and CSA's were quantified. Group differences were assessed using multi-factorial ANOVA and Tukey HSD post hoc. RESULTS: The CSA of pooled type-II fibers was 18% lower (p< 0.05) in stimulated TA's (i.e., Con-Stim), compared with contralateral controls. Importantly, this effect was absent in the Cr-Stim group. Further analysis revealed the effect was greatest within the type-IID/X fiber population, where a 24% decrease (p< 0.05) in CSA was noted in Con-Stim, while no difference was detected between stimulated and unstimulated TA's within the Cr-Stim group. Our morphological findings are consistent with measured 6% (p< 0.05) and 30% (p< 0.05) increases in whole muscle MyHC-IId/x protein and mRNA contents, respectively. CONCLUSION: Cr loading of fast-twitch muscle during endurance training exerts a protective effect on IID/X fibers. Funded by NSERC and AHFMR.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".